Many conventional stands, for example those for surgical microscopes for ophthalmology, have at their free end, between the microscope and the vertical stand support, an X-Y displacement unit for the microscope. The purpose of this displacement unit is to position the microscope in the X-Y direction in the millimeter range. This kind of arrangement of the X-Y displacement unit is generally irritating to a user, since both visibility and freedom of movement are restricted. In addition, the X-Y displacement unit considerably increases the weight on the extension arm, and usually must be compensated for by way of a corresponding counterweight or supported by a stand foot of corresponding size. As a consequence, the entire carrier arm structure of the stand beam, and optionally also the entire stand foot structure, must therefore also have greater dimensions and, in particular, a larger area.
It is therefore the object of the invention to find a stand construction in which the X-Y shifting function is retained, but any considerable weight increase in the carrier arm construction, and the further disadvantages resulting therefrom, are avoided.
In this context, the invention is not necessarily to be limited to a linear shift in two stages occurring one after the other, or to a linear displacement in general. The invention also encompasses any movements, for example calculated or controlled curved, rotary, or pivoting movements in a horizontal plane, but optionally also Z-axis shifts in a vertical plane.
The object is achieved by the relocation, according to the present invention, of the X-Y displacement unit at least closer to the vertical stand column, so that the X-Y positioning unit moves not only the microscope but also at least a portion of the horizontal stand beam.
According to the present invention, the X-Y displacement unit is not necessarily limited to carriage-like displacement tracks. It can also comprise, for example, at least two motor-driven pivot joints of the horizontal stand beam, whose mutually coordinated pivoting motions allow any desired change in the position of the microscope in an X-Y plane. The advantage of such motorized drives, with integrated incremental transducers and a corresponding control system, lies in their low weight and in a relatively more favorable cost as compared to X-Y linear displacement units.
In a preferred embodiment, the horizontal stand beam is extended, in a manner heretofore not generally common in ophthalmology microscopes, out beyond the vertical stand column and equipped there with a counterweight, so that the X-Y shifting device engages below or at least in the vicinity of the center of gravity of said extended horizontal beam.
A further improved embodiment couples the horizontal stand beam to the support for the counterweight in such a way that pivoting of the microscope results in a pivoting of the counterweight in the compensating direction for purposes of dynamic weight balancing.
The relocation of the X-Y shifting unit can also be applied independently of the pivotability of the extended horizontal beam, and vice versa.
The manner of achieving the aforesaid object is protected in the combination of features of Claim 1. It is possible by way of the invention to reduce the weight and volume on the load arm of the stand, and in that fashion to make the overall stand structure smaller. Any counterweight devices, and optionally the stand foot as well, are decreased in terms of dimensions and weight.
In addition, the need to convey electrical control lines by way of the horizontal stand carrier arm for the drive systems in the X-Y displacement unit is eliminated. The overall construction thereby becomes lighter and more compact. The invention is already satisfied to a first approximation if the X-Y displacement unit is arranged physically between the microscope and the vertical stand column. A stand beam can, for example, be of interrupted configuration, the one part being joined to the stand column and carrying the X-Y displacement unit, and other part being carried by the X-Y displacement unit.
What is preferred, however, is a configuration in which the X-Y displacement unit is arranged approximately in the axial region of the stand column. It can in this context be arranged in the region of the stand column, or can also be arranged below the stand column and support it. The latter variant has the advantage that the weight of the X-Y displacement unit is located as low down as possible; the variant with the X-Y displacement unit arranged at the top, on the other hand, has the advantage that less mass needs to be moved in the X-Y direction.
In any case, the arrangement of the X-Y displacement unit in the axial region of the stand column is advantageous, since the displacement unit itself does not need to be balanced out at that location.
The invention is not limited to stands having two-armed stand beams, i.e. having stand beams that carry the load on one arm and a counterweight on another arm. Any other stand construction is, of course, also suitable. What is essential to the invention is the location at which the X-Y displacement unit is attached.
According to an embodiment of the invention (also applicable independently) with a two-part stand beam, the two parts of the beam are pivotable with respect to one another, the pivotability being linkage-coupled. In other words, pivoting of the load in a specific direction causes the counterweight to pivot in the opposite direction, so as thereby once again to compensate for the physical shift in weight.
Since surgeons, in practical applications, prefer to have the X axis transverse to the longitudinal axis of the patient and the Y axis coaxial therewith, in one exemplary embodiment any rotation of the horizontal stand beam is performed about the axis of the displacement unit, so that its coordinate system is not affected.
In the case of a physical embodiment by way of a fixed axis in the stand column, or if the X-Y displacement unit is split into at least two pivot joints located in the horizontal stand beam arm, the corresponding displacement vectors are determined by computer, and are established automatically with computer assistance.
Further features of the invention, and variant embodiments, are described and protected in the dependent claims. Further features and patentable details are evident from the Figures and the description thereof.
The description of the Figures is overlapping. Identical reference characters denote identical components; reference characters with different indices denote components having the same functions but different physical configurations.